Polyethers are important industrial intermediates. Use as a constituent of surface-active molecules such as polyether siloxanes may be mentioned for example.
Polyether siloxanes have long been known in the prior art and are produced inter alia by the reaction of an SiH-functional polysiloxane with one or more unsaturated polyethers. In this transition metal-catalysed SiC linkage (Pt catalysts are advantageously used for example) of these two species quality requirements for the polyether to be hydrosilylized in terms of purity and reactivity are very high in order to allow as complete as possible a reaction of the SiH groups of the polysiloxane.
Particularly the etherification and the workup of the polyethers is beset by problems. Thus, for example, long-term thermal stress in the strongly alkaline medium (for example in the presence of sodium methoxide or NaOH) results in a partial isomerization of the allyl group of the polyoxyalkylene ether to afford the propenyl group owing to the process. The propenyl groups are then decomposed on up to a quantitative scale during the neutralization. This additionally releases propionaldehyde which is a health hazardous and odorous substance which can also have a negative effect on the reactivity of the polyether during the hydrosilylation reaction.